Corn is one of the most widely used crops in the world. Corn is an important source of livestock feed and may be converted to ethanol for fuel and industrial applications. In an attempt to meet the growing need for grain, corn growers continually seek to improve production in order to maximize yields. However, corn plants are subjected to stress conditions that negatively affect yield such as cold temperatures, drought and nutrient shortage. Further, even under ideal conditions it is desirable to maximize corn plant yields to ensure efficient use of fields and harvesting equipment.
Plant growth regulators are one tool that corn growers can use in order to influence the growth of their plants. However, the effects of plant growth regulators vary due, in part, to the physiology and developmental stage of the plant. Additionally, mixtures of growth regulators often have a different effect on the physiology than the individual compounds.
Gibberellins are endogenous corn plant growth regulators with many roles in growth and development. For example, GA3 stimulates the aleurone cells of germinating grains to produce lytic enzymes that mobilize starch reserves and stimulate the growth of the embryo, causing seed germination. Examples of effective commercially available GA3 formulations include ProGibb® 40% and RyzUp SmartGrass® (both available from Valent BioSciences Corporation, ProGibb and RyzUp SmartGrass are registered trademarks of Valent BioSciences Corporation). A4 is the active gibberellin in many plant species and exogenous application induces similar growth promotion to GA3.V Examples of effective commercially available GA4 containing formulations include ProVide® and Regulex® (both available from Valent BioSciences Corporation, ProVide and Regulex are registered trademarks of Valent BioSciences Corporation). Application of GA3, to vegetative phase corn has been shown to increase plant height (see Kaiser et al., International Patent Application WO 2014/120882).
Glycine betaine (“GB”) (CAS No. 107-43-7) is a solute that accumulates in plants, micro-organisms and fungi in response to abiotic stress. Exogenous application of GB to plants has been shown to confer abiotic stress tolerance (Chen and Murata, 2008. Trends in Plant Sciences 13: 499-505). Specifically, GB induces resistance to chilling, freezing, and drought across multiple plant species. However, the levels of stress protection observed, although significant, are of limited commercial value. GA3 is a plant growth regulator that also confers tolerance to a variety of stresses. In the studies disclosed here, GB increases both the anti-stress activity and the growth-promoting activity of gibberellins. To our knowledge this is a novel use of GB. Corn growers constantly strive to increase yield of either grain or silage due to both high demand and the costs associated with production. Accordingly, there is a need for new methods to improve the growth of corn under non-stressed and stressed conditions.